The term “oxygen scavenging” means to absorb, deplete, or react with oxygen from a given environment.
Oxygen scavenging materials have been developed partly in response to the food industry's goal of having longer shelf-life for packaged food. One method which is currently being employed involves the use of “active packaging” where the package is modified in some way so as to control the exposure of the product to oxygen. Such “active packaging” can include sachets containing iron-based compositions such as AGELESS™ which scavenges oxygen within the package through an oxidation reaction. However, such an arrangement is not advantageous for a variety of reasons including the accidental ingestion of the sachets or the oxygen scavenging material present therein.
Other techniques involve incorporating an oxygen scavenger into the package structure itself. In such an arrangement, oxygen scavenging materials constitute at least a portion of the package, and these materials remove oxygen from the enclosed package volume which surrounds the product or which may leak into the package, thereby, in the case of food products, inhibiting spoilage and prolonging freshness.
Oxygen scavenging materials include low molecular-weight oligomers that are typically incorporated into polymers or can be oxidizable organic polymers. Such oxygen scavenging materials are typically employed with a suitable catalyst, e.g., an organic or inorganic salt of a transition metal catalyst.
The onset of useful oxygen scavenging activity may not occur for as long as 30 days. In order to shorten the induction period and to initiate oxygen scavenging, photoinitiators can be employed in conjunction with actinic radiation. Many of these photoinitiators and resulting by-products are extractable and can leach into the headspace surrounding the packaged product or even enter the product itself. Such leaching can produce foul odors or unpleasant taste or can be otherwise undesirable.